📄 genetic and genomic medicine

Evaluating ANO6 as a Parkinson's disease candidate gene: a human genetic investigation of common and rare variant associations

This large-scale human genetic investigation concludes that despite initial signals of common and rare variant associations, ANO6 does not play an important role in Parkinson's disease risk, as common variant signals were driven by linkage disequilibrium with LRRK2 and rare variant enrichment lacked functional specificity.

Original authors: Parlar, S. C., Leonard, H., Senkevich, K., Liu, L., Teferra, M., The Global Parkinson's Genetics Program (GP2),, Gan-Or, Z.

Published 2026-01-23

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CC BY 4.0

Original authors: Parlar, S. C., Leonard, H., Senkevich, K., Liu, L., Teferra, M., The Global Parkinson's Genetics Program (GP2),, Gan-Or, Z.

Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). ⚕️ This is an AI-generated explanation of a preprint that has not been peer-reviewed. It is not medical advice. Do not make health decisions based on this content. Read full disclaimer

Imagine the human body as a massive, bustling city. In this city, there are specific delivery trucks that carry a cargo called alpha-synuclein. In Parkinson's disease, these trucks start malfunctioning, spilling their cargo and causing traffic jams (aggregates) that clog up the streets of the brain.

For a long time, scientists have been looking for the "traffic controllers" or the "drivers" that might be causing these trucks to spill. Recently, a new suspect was identified: a protein called ANO6. Think of ANO6 as a specialized gatekeeper at the cell's front door. Its job is to manage the flow of lipids (fats) and ions, and recent lab experiments suggested that if this gatekeeper gets too active, it might accidentally help the bad alpha-synuclein cargo escape the cell and spread to neighbors.

A specific "typo" in the ANO6 instructions (a genetic variant called p.Ala703Ser) was even found in some patients, making the gatekeeper work too hard. This made scientists wonder: Is ANO6 actually a major cause of Parkinson's disease in the general population?

To answer this, the researchers in this paper acted like massive-scale detectives. They didn't just look at a few people; they examined the genetic blueprints of hundreds of thousands of individuals to see if the ANO6 "gatekeeper" was truly linked to the disease.

Here is what they found, broken down into two main investigations:

1. The "Common Variants" Investigation (The Neighborhood Watch)

First, the team looked at common genetic variations. Imagine these as the standard, everyday typos found in many people's instruction manuals. They scanned the data of over 63,000 Parkinson's patients and 1.7 million healthy people.

The Initial Clue: They found seven specific spots in the ANO6 gene that seemed to be strongly linked to Parkinson's. It looked like a smoking gun!
The Twist: However, when they zoomed in, they realized these seven spots were actually just "shadowing" a famous, well-known suspect named LRRK2.
The Metaphor: Think of LRRK2 as a very loud, famous celebrity living in the same neighborhood as ANO6. Because they live so close together, the genetic "noise" from the celebrity (LRRK2) was drowning out the quiet signals of the neighbor (ANO6). The researchers found that the ANO6 signals were only significant because they were hitching a ride on the LRRK2 signal.
The Result: Once they mathematically "silenced" the LRRK2 celebrity to see what ANO6 was doing on its own, the ANO6 signals disappeared. The common variations in ANO6 are not a direct cause of Parkinson's risk.

2. The "Rare Variants" Investigation (The Hidden Defects)

Next, the team looked for rare genetic variations. These are like unique, one-of-a-kind typos that only a few people have. They analyzed the full genetic code (Whole Genome Sequencing) of nearly 5,000 patients and 65,000 controls.

The Initial Clue: When they lumped all the rare typos in ANO6 together, they saw a tiny, statistically significant signal. It was like finding a few broken bricks in a massive wall.
The Catch: When they tried to sort these broken bricks by type (e.g., "broken load-bearing bricks" vs. "broken decorative bricks"), the signal vanished. The only time they saw a link was when they counted every single rare typo, including the ones that don't seem to do anything important (non-coding variants).
The Metaphor: It's like finding that a house has a leak, but when you check the roof, the walls, and the pipes, nothing is broken. The only reason the house seems wet is because you counted a few drops of rain that fell on the driveway (non-coding DNA) and included them in the total.
The Result: The researchers concluded that this rare signal is likely a "false alarm" or a statistical fluke, especially since it didn't show up in the most dangerous categories of genetic errors.

The Final Verdict

The paper concludes that ANO6 is likely not a major player in causing Parkinson's disease in humans, despite the earlier lab experiments suggesting it might be.

The "common" signals were just a case of mistaken identity, confused with a different gene (LRRK2).
The "rare" signals were too weak and inconsistent to be trusted as a real cause.

In short: While ANO6 might play a role in a petri dish or in very specific, rare cases, the massive genetic evidence from the general population suggests it is not a primary driver of Parkinson's disease. The "gatekeeper" is probably not the one letting the bad cargo out in the way scientists originally hoped.

Technical Summary: Evaluating ANO6 as a Parkinson's Disease Candidate Gene

Problem Statement
Parkinson's disease (PD) is a complex progressive movement disorder with significant unexplained heritability. While over ten genes have been definitively implicated in PD etiology, recent functional studies by Cohen-Adiv et al. (2025) suggested a potential role for ANO6 (also known as TMEM16F). ANO6 encodes a Ca²⁺-activated lipid scramblase and ion channel involved in phospholipid externalization and membrane dynamics. Cohen-Adiv et al. (2025) demonstrated that ANO6 modulates extracellular α-synuclein and its neuron-to-neuron propagation, a hallmark of PD pathology. Furthermore, a specific missense variant, p.Ala703Ser, associated with increased scramblase activity, was identified in Ashkenazi Jewish PD patients. The central question addressed by this study is whether human genetic variation in ANO6—encompassing both common and rare variants—converges with these functional findings to support a causal role for ANO6 in PD risk.

Methodology
The authors employed a two-pronged genetic approach utilizing large-scale datasets to assess ANO6 association with PD.

Common Variant Analysis (GWAS):
- Data Source: Genome-wide association study (GWAS) summary statistics from the Global Parkinson's Genetics Program (GP2), comprising 63,555 PD cases, 17,700 proxy cases, and 1,746,386 controls.
- Analysis: The authors visualized locus-wide signals using LocusZoom.js and identified variants reaching genome-wide significance ( $P < 5 \times 10^{-8}$ ).
- Conditional Analysis: Given the proximity of the well-established PD risk variant LRRK2 p.G2019S (~4.9 Mb away) and known extended linkage disequilibrium (LD) blocks at this locus, the authors conditioned the ANO6 signals on the p.G2019S variant. This was performed using genotyping array data from GP2 Release 10, specifically analyzing Non-Finnish European and Ashkenazi Jewish ancestries (1,813 cases/996 controls and 26,358 cases/20,088 controls, respectively).
Rare Variant Burden Analysis:
- Data Source: Whole-genome sequencing (WGS) data from two cohorts: the UK Biobank (UKBB) and the Accelerating Medicines Partnership for Parkinson's disease (AMP-PD). The analysis included 4,879 PD cases and 65,279 controls of European ancestry.
- Variant Filtering: Variants were restricted to the ANO6 gene region (chr12:45,216,322–45,429,308) with a minor allele frequency (MAF) < 0.01.
- Functional Categorization: Variants were grouped into five categories: (1) all rare variants, (2) non-synonymous coding variants, (3) CADD ≥ 20 (top 1% predicted deleterious), (4) AlphaMissense predicted likely pathogenic, and (5) loss-of-function (LoF) variants.
- Statistical Testing: Burden analysis was conducted using the optimized sequence kernel association test (SKAT-O) at the cohort level, followed by meta-analysis using MetaSKAT. Analyses were adjusted for sex, age, and LRRK2 p.G2019S carrier status. False discovery rate (FDR) corrections were applied.

Key Results

Common Variant Signals: Seven noncoding common variants within ANO6 initially reached genome-wide significance. However, allele frequency analysis revealed these risk alleles were significantly more frequent in the Ashkenazi Jewish population compared to Non-Finnish Europeans. Upon conditioning for the LRRK2 p.G2019S variant, the significant associations in the ANO6 region were completely abolished in both ancestries. This confirms that the initial GWAS signals were driven by LD with the LRRK2 p.G2019S variant rather than independent ANO6 effects.
Rare Variant Burden:
- A significant enrichment was observed only when aggregating all rare variants (meta-analysis $P_{FDR} = 0.02$ ).
- No significant signals were detected in any functional sub-categories (non-synonymous, CADD ≥ 20, AlphaMissense, or LoF).
- The specific p.Ala703Ser variant reported by Cohen-Adiv et al. (2025) was observed in AMP-PD (2 cases, 4 controls) but not in UKBB; no enrichment was evident based on case-control counts.
- Adjusting for LRRK2 p.G2019S carrier status did not alter the rare variant burden outcomes.
Limitations: The study notes that rare variant analyses were restricted to European ancestry, potentially limiting generalizability to other populations. Additionally, differences in quality control protocols between UKBB and AMP-PD cohorts may introduce variability.

Significance and Conclusion
The authors conclude that human genetic data does not support a major role for ANO6 in Parkinson's disease risk. The study demonstrates that the previously observed common variant associations are artifacts of linkage disequilibrium with the established LRRK2 p.G2019S risk variant. While a nominal signal was detected for the aggregation of all rare variants, the lack of signal in functional categories (including the specific missense variant p.Ala703Ser) and the potential for spurious noncoding associations suggest that ANO6 likely has a minor or negligible role in PD pathogenesis. Consequently, the recent functional evidence implicating ANO6 in α-synuclein propagation does not appear to translate into a detectable genetic risk factor for PD in large-scale human populations.

1. The "Common Variants" Investigation (The Neighborhood Watch)

2. The "Rare Variants" Investigation (The Hidden Defects)

The Final Verdict

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